The invention generally relates to a large scale telecommunications network employing an optical core transport network of a fully meshed configuration. In particular, it is directed to an architecture of a large scale telecommunications network in which electronic edge switches are connected to a fully meshed optical core transport network and major control functions of each connection are performed substantially by two electronic edge switches of the connection.
The emerging data network must be able to grow to a much-higher capacity than the capacity of today""s voice and data networks. In addition to the huge-capacity requirement, the emerging networks must provide diverse and versatile services. The multiplicity of connection protocols, and the effort required for their interworking, inhibit the ability of the network to provide service diversity. The simplest network would be fully connected, allowing every networking node to have a physical connection to every other networking node. However, as the network size grows, this fully-meshed structure rapidly becomes impractical. Due to the spatial variation of traffic loads, and the typically large modular sizes of transport links, a fully-meshed network normally leads to underutilized transport facilities.
Traditional electronic transport systems can offer a meshed network by providing direct interconnections between the networking nodes. However, the connections would be based on channelized time division multiplexing, where the bandwidth allocated to a node-pair is fixed and dedicated to the node-pair, resulting in inflexible bandwidth utilization. A fully-meshed network is not scaleable to cover a large number of nodes, unless the link capacities are elastic and can be modified rapidly to follow the traffic-demand variation. With fixed capacities and fluctuating traffic demand, the transport utilization drops rapidly as the number of nodes increases. An elastic network, however, would allow all the connections to share a common pool of capacity through paths whose capacities are dynamically adjustable.
Both cross-connection-based and ring-based networks can be configured to be fully meshed or almost fully meshed. Their transport mechanisms can also be optical or electronic or a mixture of both.
U.S. Pat. No. 5,802,043, issued Sep. 1st, 1998, entitled xe2x80x9cTransport Architecture and Network Elementsxe2x80x9d, has an inventor common to the present application and describes one such solution based on an optical ring structure with capacity partitioning. In its realization, a domain is defined where every networking node within the domain is connected to every other networking node within it with fixed or variable capacity. All the connections within the domain share a common pool of capacity, maximizing the utilization of the node interfaces. Various networking nodes which use different protocols, such as ATM or IP, are accommodated by defining a container structure which carries digital information in its native form between them. The containers are carried on a digital facility with a defined bit rate that circulate on a ring or virtual ring past every networking node in the domain.
A pending U.S. patent application Ser. No. 09/116,477 entitled xe2x80x9cProgrammable Transport and Network Architecturexe2x80x9d and filed on Jul. 16, 1998 with the common inventors extends further the meshed networking based on an optical ring configuration. The subject matter is described in an article xe2x80x9cArchitecture and Control of an Adaptive High-Capacity Flat Networkxe2x80x9d IEEE Communications Magazine, May 1998. The meshed network of this patent application allows all the connections to share a common pool of capacity through links among nodes whose capacities are dynamically adjustable. Nodes provide data packaging into xe2x80x9ccontainersxe2x80x9d of fixed or variable sizes for transport and a ring exchanges data containers among its nodes. A centralized or distributed controller calculates a service rate for each source-destination node pair. Such controller either monitors the traffic or receives updated capacity-allocation requests from the nodes, and assigns an appropriate data rate at which each node can transmit to each destination. With lossless rings (traffic-wise), the quality of service is controlled by the source and destination nodes, without any interference from other data streams within the network. By reducing the complexity of the network core, an economical, reliable, and manageable network with feature-rich edge nodes can be realized.
In the IEEE article referenced above, it was stated that:
Unprecedented traffic growth is providing a huge demand for fiber facilities. Not only are the backbone networks outstripping their original design capacities, but the routes will need fiber cable replacements to allow full buildup of high-density WDM. In addition, as the routes grow, there will be further pressures to create better diversity to improve restoration. Currently, WDM is primarily used to increase point-to-point transport capacity. The abundance of transport bandwidth due to WDM may justify a highly-meshed topology at wavelength granularity. However, due to the spatial traffic variation and with wavelength switching, a wide-coverage network may still require tandem switching and capacity-sharing controls, which are now realized electronically. Two dimensional space-WDM switching nodes may be used to realize, at a wavelength granularity, either a partially-interconnected network or a fully-meshed network.
WDM stands for wavelength division multiplexing and refers to the technique of sending simultaneously a beam or beams of light of more than one wavelength through one optical fiber.
In U.S. Pat. No. 5,751,454 May 12, 1998, MacDonald et al, an optical ring network communication structure is described in which multiple wavelengths travel in one direction and wavelength Mux/Demux is performed at each node. In addition to being able to add and drop any wavelength, however, each node also has the ability to bypass selected wavelengths. By bypassing selected nodes, a direct channel of one wavelength can be provided between any node pair if the total number of nodes on the ring is relatively small.
U.S. Pat. No. 5,760,935 Jun. 2, 1998 Sabry et al describes an optical communications network in which information is transported through hierarchically configured networks via pixels in a discrete communications space defined by time and wavelength coordinates.
In U.S. Pat. No. 5,760,934 Jun. 2, 1998 Sutter et al describe an optical ring network using wavelength division multiplexing technique.
Generally speaking, a network with N nodes requires a minimum of N(N-1) paths to achieve a fully meshed configuration, where there is always a dedicated path available in each direction for each of a node pair. For example, in the case of 7 nodes in a network, 42 unidirectional paths are needed for all the possible node pairs, resulting in 21 bidirectional paths.
According to a broad aspect, the present invention realizes a fully meshed network, which provides an end-to-end path of an arbitrary capacity for each node pair. The capacity of each path may be dynamically modified in response to traffic loads and other network conditions. Each node must then sort its traffic according to destination, into logical buffers, and regulate the rate at which traffic is sent from each buffer.
In U.S. Pat. No. 5,760,934 Jun. 2, 1998 Sutter et al describes an optical ring network using wavelength division multiplexing technique.
It is therefore an object of the invention to provide a fully meshed telecommunications network in which an optical core transport network is used and a channel is managed by a pair of electronic edge switches at the ends of the channel.
It is a further object of the invention to provide a fully meshed telecommunications network in which an optical dual ring is used as the core transport network and a channel is managed by a pair of electronic edge switches at the ends of the channel.
It is another object of the invention to provide a fully meshed telecommunications network in which an optical dual ring is used as the core transport network and carries wavelength multiplexed optical signals.
It is yet an object of the invention to provide a fully meshed telecommunications network in which an end-to-end rate regulation is performed between a pair of electronic edge switches.
It is still a further object of the invention to provide a fully meshed telecommunications network in which a multiple of optical dual rings, operating in parallel, is used as the core transport network and carries wavelength multiplexed optical signals.